In order to reduce protein deficiency in nutrition or to terminate it, thorough and significant research is being carried out throughout the world. One of the most obvious ways to achieve this objective is the use of additives to nutrients and feed which improve the utilization of the nutrients introduced into the organism. In animal husbandry, these additives result in a higher body-weight increase for an identical feed consumption and breeding period.
However, it has been rather difficult to develop an appropriate substance for increasing animal body weight since the use of substances with hormonal effects and of antibiotics is not permitted in most of the countries.
Isoflavone compounds have been subjected to a detailed investigation from the aspect of their body-weight increasing effect. These compounds are rather widespread in plants, and a great number of them show oestrogenic properties. (cf. Virtanen, A. J.: Angew. Chem. 30, 544, (1958); Virtanen, A. J., Hietala, P. K.: Acta Chem. Scand. 12, 579, (1958). Grazing animals become infertile on consuming certain varieties of clover; research into this problem has shown that genistein and daidzein present in the plants consumed by pasturing animals are responsible for this effect because of their marked oestrogenic action (Chang, E. W. et al.: Ann. N.Y. Acad. Sci. 61, 625, 1955).
For the determination of the oestrogenic effect of isoflavones a reliable method has been evolved by East, J. (J. Endocrin. 13, 94, 1955). Since that time a number of authors have dealt very thoroughly with this problem (Matrone, G. et al.: Nutrition 59, 235, 1956; Gabor, M.: Naturwise. 461/2 650, 1959; Crabb, P. et al.: J. Am. Chem. Soc. 85, 5258, 1958).